`timescale 1ns/1ps

module tb_led();

reg key;
wire led;

led u_led(
    .key(key),
    .led(led)
);

initial begin
    key <= 1'b0;
    #1000
    key <= 1'b1;
    #1000
    key <= 1'b0;
    #1000
    key <= 1'b1;
end

endmodule